All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.
First of all, it should be noted that the Sharee’ah urged and encouraged us to conceal our sins and forbade the spread of evil acts and immorality among the believers; Allaah Says (what means): {Indeed, those who like that immorality should be spread [or publicized] among those who have believed will have a painful punishment in this world and the Hereafter. And Allaah knows and you do not know.}[Quran 24:19] For more benefit on this issue, please refer to Fatwa 89638.
Hence, it is not permissible for a spouse to ask the other about the sins that he/she had committed in the past or the sins that he/she does at the present time as this contradicts that great Islamic objective. Moreover, this could lead to the spread of suspicion between them and them not trusting each other. In principle, a Muslim male or female is innocent until proven otherwise. Besides, suspicion is Islamically dispraised; Allaah Says (what means): {O you who have believed, avoid much [negative] assumption. Indeed, some assumption is sin.}[Quran 49:12]
Indeed, suspicion leads to the husband considering his wife as unfaithful and vice-versa. It leads also to each one of them spying on the other and to other matters that are not permissible.
On the other hand, it should be noted that some jealousy is praised and some jealousy is dispraised: the praised jealousy is that which happens at times of justifiable doubt and the dispraised one is that which happens at times when there is no justifiable doubt as we clarified in Fatwa 90757.
In case any of the spouses knows that the other has committed a forbidden matter, then he/she should advise him/her, remind him/her of Allaah, and incite him/her to repent. Indeed, religion is advice as confirmed in a Hadeeth of the Prophet and which was reported by Imaam Muslim .
Allaah Knows best.